Method and apparatus for control of flow through a filter chamber by measured chamber equilibration pressure

Abstract

A method and apparatus for the controlled instrumentation processing of cells and other paricles with a filter device measures a parameter of the flow through the filter device of a fluid carrying the particles. A measure of the change of fluid flow through the filter device yields desired information for quantizing the particles and for quantizing the obstruction of the filter device by the particles. The method and apparatus typically operate automatically.

Having described the invention, what is claimed as new and secured by Letters Patent is: 
     
       1. Apparatus for supplying a selected sequence of pressure conditions to a filter device for controlling the flow of particle-containing fluid through the filter device, said apparatus comprising A. means forming a filter chamber having pressure port means and having a filter device forming a chamber wall thereof and having a porosity for blocking particles of selected size, said filter chamber being arranged for fluid to flow into the interior thereof through said filter device,   B. pressure source means arranged with valve means for selectively applying a source pressure to said chamber interior by way of said pressure port means, said source pressure being different from a first pressure in said filter chamber and producing a flow of fluid greater than any flow occurring during presence of said first pressure, and   C. control means arranged for sensing the chamber interior pressure and connected with said valve means, said control means being arranged for executing a cycle of successive operations including (i) a first step of opening said valve means for applying said source pressure to said chamber interior for producing a selected fluid flow through said filter device,   (ii) a second step of closing said valve means for allowing a flow of fluid through said filter device for equilibrating the chamber pressure in a direction from said source pressure toward said first interior pressure,   (iii) a third step of measuring an equilibration time in which said chamber pressure equilibrates from said source pressure to a second chamber pressure intermediate said first pressure and said source pressure, said equilibration time corresponding to a degree of blockage of said filter device by the particles, and   (iv) repeating said first and second and third steps only in response to an equilibration time, as measured in said third step, less than a predetermined time value.     
     
     
       2. Apparatus according to claim 1 further comprising A. means forming plenum means arranged with plenum valve means for selectively coupling said plenum means with said filter chamber, and   B. means for establishing in said plenum means, at least prior to the initial occurrence of said first step, a pressure for producing said first pressure in said filter chamber,   C. said control means being further arranged for executing said cycle of operations including (i) closing said plenum valve means during said first step, said second step and said third step, and   (ii) opening said plenum valve means for coupling said plenum means with said filter chamber after said measured chamber interior pressure has reached said second chamber pressure.     
     
     
       3. Apparatus according to claim 2 in which said filter chamber has a first volume and in which said plenum means has a volume at least one order of magnitude greater than said first volume. 
     
     
       4. Apparatus according to claim 1 further comprising plenum means coupled in parallel with said filter chamber. 
     
     
       5. Apparatus according to claim 1 further comprising A. first plenum means coupled in parallel with said filter chamber,   B. second plenum means arranged with plenum valve means for selectively coupling said second plenum means with said filter chamber, said filter chamber and said first plenum means together having a first combined volume, and said second plenum means having a volume at least one order of magnitude greater than said first combined volume, and   C. means for establishing in said second plenum means, at least prior to the initial occurrence of said first step, a pressure for producing said first pressure in said filter chamber,   D. said control means being further arranged for executing said cycle of operations including (i) closing said plenum valve means during said first step, said second step and said third step, and   (ii) opening said plenum valve means for coupling said second plenum means with said filter chamber after said measured chamber interior pressure has reached said second chamber pressure.     
     
     
       6. Apparatus for measuring the occlusion of a filter device by particles contained in a fluid flowing through the filter device, said apparatus comprising A. means forming a filter chamber having a filter device forming a chamber wall thereof and having a porosity for blocking particles of selected size, said filter chamber being arranged for fluid to flow into the interior thereof through said filter device,   B. pressure source means arranged with valve means for selectively applying a flow-producing pressure differential across said filter device, said flow-producing pressure differential being different from a first pressure differential across said filter device and producing a flow of fluid greater than any flow occurring during presence of said first pressure differential, and   C. control means arranged for sensing a pressure differential across said filter device and connected with said valve means, said control means being arranged for executing a cycle of successive operations including (i) a first step of opening said valve means for applying said flow-producing pressure differential across said filter device for producing a selective fluid flow through said filter device,   (ii) a second step of closing said valve means for allowing a flow of fluid through said filter device for equilibrating the pressure differential in a direction from said flow-producing pressure differential toward said first pressure differential,   (iii) a third step of measuring an equilibration time in which said pressure differential equilibrates from said flow-producing pressure differential to an equilibration pressure differential intermediate said first pressure differential and said equilibration pressure differential, and   (iv) repeating said first and second and third steps only in response to an equilibration time, as measured in said third step, less than a predetermined time value.     
     
     
       7. A method for supplying a selected sequence of pressure conditions to a filter device for controlling the flow of particle-containing fluid through the filter device, said method comprising A. providing a filter chamber having pressure port means and having a filter device forming a chamber wall thereof and having a porosity for blocking particles of selected size, said filter chamber being arranged for fluid to flow into the interior thereof through said filter device,   B. providing a pressure source arranged with valve means for selectively applying a source pressure to said chamber interior by way of said pressure port means, said source pressure being different from a first pressure in said filter chamber and producing a flow of fluid greater than any flow occurring during presence of said first pressure,   C. providing control means arranged for sensing the chamber interior pressure and connected with said valve means,   D. operating said control means through a cycle of successive operations including (i) a first step of opening said valve means for applying said source pressure to said chamber interior for producing a selected fluid flows through said filter device,   (ii) a second step of closing said valve means for allowing a flow of fluid through said filter device for equilibrating the chamber pressure in a direction from said source pressure toward said first interior pressure,   (iii) a third step of measuring an equilibration time in which said chamber pressure equilibrates from said source pressure to a second chamber pressure intermediate said first pressure and said source pressure, and   (iv) repeating said first and second and third steps only in response to an equilibration time, as measured in said third step, less than a predetermined time value.